Patterned and topographic organization of neural connections is an essential structural substrate for processing sensory information in the brain. The long-term objective of this proposal is to determine cellular mechanisms underlying the establishment of such neural networks in the somatosensory system. In the rodent trigeminal system, the spatial organization of the mystacial vibrissae on the snout is replicated in a one-to-one fashion by neural modules found in the brainstem trigeminal nuclei, the dorsal thalamus, and the somatosensory cortex. In this research we shall use the trigeminal brainstem from transgenic and knockout mice to reveal specific cellular mechanisms underlying pattern formation and structural plasticity during development. Combined electrophysiological, pharmacological and anatomical techniques will be used to chart out membrane properties, synaptic responses, and NMDA receptor and L-Type calcium channel-mediated response characteristics. A clear understanding of cellular and molecular events during coupling of select sets of pre and postsynaptic elements that form sensory periphery-related patterns is a key step in delineating how specific neuronal assemblies form in the mammalian brain, and how these neuronal assemblies are modified following peripheral nerve injury. A solid understanding of these mechanisms is critical for preventing or repairing often-irreversible effects of damage to the developing human nervous system.